Cloud infrastructure refers to the hardware and software components -- such as servers, storage, a network, virtualization software, services and management tools -- that support the computing requirements of a cloud computing model.
Cloud infrastructure also includes an abstraction layer that virtualizes and logically presents resources and services to users through application program interfaces and API-enabled command-line or graphical interfaces.
In cloud computing, these virtualized resources are hosted by a service provider or IT department and are delivered to users over a network or the internet. These resources include virtual machines and components, such as servers, memory, network switches, firewalls, load balancers and storage.
Cloud infrastructure components
In a cloud computing architecture, cloud infrastructure refers to the back-end hardware elements found within most enterprise data centers, but on much greater scale. These include multisocket, multicore servers, persistent storage and local area network equipment, such as switches and routers.
Major public cloud providers, such as Amazon Web Services (AWS), Microsoft Azure and Google Cloud Platform, offer services based on shared, multi-tenant servers. This model requires massive compute capacity to handle both unpredictable changes in user demand and to optimally balance demand across fewer servers. As a result, cloud infrastructure typically consists of high-density systems with shared power.
A view of a typical cloud infrastructure, which includes servers, applications, clients and other components.
Additionally, unlike most traditional data center infrastructures, cloud infrastructure typically uses locally attached storage, both solid-state drives (SSDs) and hard disk drive (HDDs), instead of shared disk arrays on a storage area network. The disks in each system are aggregated using a distributed file system designed for a particular storage scenario, such as object, big data or block. Decoupling the storage control and management from the physical implementation via a distributed file system simplifies scaling. It also helps cloud providers match capacity to users' workloads by incrementally adding compute nodes with the requisite number and type of local disks, rather than in large amounts via a large storage chassis.
Public vs. private vs. hybrid cloud architectures
Cloud infrastructure is present in each of the three main cloud computing deployment models: private cloud, public cloud and hybrid cloud. In a private cloud, an organization typically owns the cloud infrastructure components and houses them within its own data center. In a public cloud model, the cloud infrastructure components are owned by a third-party public cloud provider. A hybrid cloud consists of a mix of both models working together to form a single logical cloud for the user.
Cloud infrastructure as a service
While cloud infrastructure is the hardware and software components required for cloud computing, infrastructure as a service (IaaS) is the delivery model by which organizations can deliver those cloud infrastructure components, including compute, storage and networking, over a dedicated internet connection. Components, resources and services delivered from the cloud typically carry recurring periodic costs to the user, allowing providers to generate revenue through rental or other "pay as you go" models.
On top of those basic cloud infrastructure services, providers offer an array of more granular, specialized services. Examples include container infrastructure, service fabrics, serverless functions, and managed network services (virtual private clouds, load balancers, domain name services, application delivery controllers, firewalls).
Cloud providers typically price IaaS on a metered basis, with rates corresponding to usage at a given level of performance. For virtual servers, this means different